Method of making expansible diaphragms



INVENTOR. I

ATTORNEY July' 12, 1938. w. A. REICHE L V METHOD OF' MAKING EXPANSIBLE DIAPHRAGMS Original Filed Jan. 22, 1932 25 a manner that in operation the sealed connection Patentcd July 12, 1938 UNITED STATES PATENT OFFICE METHOD OF MAKING EXPANSIBLE DIAPHRAGMS Wladimir A. Reichel, Philadelphia, Pal, assignor to Bendix Aviation Corporation, South Bend, Ind., a. corporation of Delaware 1935, Serial No. 31,129

8 Claims. (Cl. 29-1482) the cause of very serious results following re- The present invention relates to expansible and contractible diaphragm devices such as are discl'osed in my co-pending application Serial No. 588223, filed January 22, 1932, now Patent No. 2,070,751 dated February 16, 1937, of which the present application is a division, and more particularly to a method of making such diaphragm devices.

` Diaphragm devices made in accordance with the method of the invention are particularly suitable for use in certain types of precision measuring instrumente such as sensitive pressure gauges, aneroid barometers, hydrostatic fuel-lever gauges, air speed indicators, altimeters, rate of climb instruments, and in any other instruments employing a pressure sensitive element.

A'common method employed heretoiore, in making diaphragm devices of the above type was to unite together two fiexible metallic diaphragms having rim portions extending axially of the diaphragm device and out of the planes of the diaphragms in overlapping relation.

Another common method was to connect and seal the peripheral edges of the diaphragms to an immediate cooperating shell structure in such i was stretched or strained in tension, i. e.,- when a pressure was exerted inside of the diaphragm device the peripheral edges tended to pull away from the supporting shell, thereby tending to break the sealed connection between the diaphragms and` the shell.

In the first method it has been endeavored to make and maintain the diaphragm devices airtight by sealing the two overlapping rims of the diaphragms, and in the second method by scaling the peripheral edges of the diaphragms to the exterior surface of the supporting shell. It has' been frequently found, however, that expansible diaphragm devices made in accordance with the first method failed because of leaks occurring as a result of the parting of the bond between the sealed rim portions, and those made in accordance with the second method generally failed eter, for example, these errors may amount to several hundred feet which would render the instrument wholiy unreliable and might even be:

liance upon the reading of such a defective instrument particularly in an aircrait during a manoeuvre. consequently lt is of the greatest importance that diaphragm devices be so made as to be able to withstand rigorous tests and extreme conditions, such as are due to high vibration and changes in pressures and temperature to which aeronautical instruments particularly are subjected.

Accordingly one of the objects of the present invention is to provide a novel method of making the same, whereby the foregoing difliculties are substantially eliminated and whereby instruments embodying such diaphragm devices are rendered more precise.

Another object is to provide, in accordance with the method of the invention, an expansible and contractible diaphragm device having a novel sealed connection which is not stretched, strained nor disturbed in any manner during normal operation of the diaphragms constituting the diaphragm device, thereby preventng errors due to leaks and hysteresis.

Another object is to provide a novel method of making an expansible and contractible diaphragm device which has its oppositely dlsposed diaphragms Secured to a supporting shell by a sealed connection in such a manner'that the force created 'by' the pressure preponderating inside of the device tends to press the peripheral edges of the diaphragm against the shell rather than away from it so that the sealed connection is compressed instead of stretched whereby delayed restitution or hysteresis is prevented and the possibility of leaks substantially eliminated.

Still another object is -to provide a `novel method of making expansible diaphragm devices which method comprises, forming a pair of corrugated fiexible diaphragms so as to have inturned peripheral flanges, securing said diaphragms to a supporting shell in such a manner that the peripheral flanges of the diaphragms abut against the interior of the shell, and placing sealing material, such as solder, at the place where the exterior surfaces of the diaphragm` flanges abut against the interior surface of the supporting shell so ,that the preponderating pressure inside of the box tends to press the flanges of the diaphragms against the supporting shell without disturbing the scaling matescription which follows, taken together with the accompanying drawing wherein are illustrated two embodiments of the invention. It is to be expressly understood, however, that the drawing is merely for the purpose of illustration and description and is not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing wherein like reference numerals refer to like parts in the two views,

Fig. 1 is a sectional view showing one form of diaphragm device embodying the present invention; and

Fig. 2 is a sectional View showing another embodiment of the invention.

The diaphragm device made in accordance with the method of the invention is constituted by a supporting member or shell, preferably cylindrical and a pair of oppositely disposed metallic diaphragms which have their peripheral edges Secured to said supporting shell. In the form shown in Fig. 1 of the drawing the supporting shell comprises a cylindrical member 3 having fiange portions 4 and 5 projecting inwardly at a suitable angle to provide an annular reinforcing wall against which the diaphragms are adapted to press when there exists a preponderating pressure inside of the diaphragm device. The diaphragms, which may be of any suitable flexible material and preferably of thin sheet copper, are indicated at 6 and 'I and are corrugated in the usual manner to provide the required fiexibility. The diaphragms are also formed, as by stamping, so as to have peripheral or rim flange portions 8 and 9 projecting out of the planes thereof and at an angle corresponding to the angle at which the fianges 4 and 5 of the supporting shell 3 are turned inwardly. The diaphragms 6 and 'l are arranged against the supporting shell 3 in such a manner that the exterior surfaces of the fianges 8 and 9 abut against the interior surfaces of the flanges 4 and 5, respectively, thereby providing a relation between the diaphragms and their supporting shell such that the former press against thelatter during normal operation of the diaphragm device.

It is pointedout that in the forming of the diaphragm device, first one flange, as for example the fiange 4, is turned in and the diaphragm 6 positioned thereagainst, and after diaphragm 6 is secured to the shell then the other diaphragm 1 is inserted into the shell 3 with its peripheral fiange 9 extending inwardly of the device and the peripheral edge of the shell 3 is then bent or spu'n to provide the peripheral fiange 5 which cooperates with fiange 9 of the diaphragm 1. The diaphragms are secured to the shell in any suitable manner as, for example, by brazing or by placing suitable scaling material, such as solder, between the inner edges of the shell flanges 4 and 5 and the outer face of the diaphragm fianges l and 9 to form two annular sealed connections indicated at o and I i. It will be noted from this arrangement that the sealed connections o and II can not be stretched or strained when movements of the diaphragms 6 and 1 occur due to preponderance of pressure inside of the diaphragm device over the pressure outside of the device as is the case in Instruments in which expansible diaphragm devices of this type are employed, the reason for this being that the fianges 4 and 5 of the supporting shell provide a reinforcement whereby the diaphragms bear against the shell during operation instead of pulling away therefrom as is the case in diaphragm devices of prior construction.

Referring to Fig. 2 wherein there is illustrated another form of expansible and contractible diaphragm devices made in accordance with the method of the invention, the supporting shell 3 is cylindrical as in Fig. 1, but is not provided with any peripheral fianges. are again formed to have peripheral fianges 8 and 9, but the width thereof is slightly less than that of the flanges shown in Fig. 1. The edges of the fianges 8 and 9 abut against the interior wall of the shell 3 so as to form an annularacute angular space therebetween for receiving the sealing material, such as solder, which forms the annular air-tight connections ll] and il. Hence, when there is a preponderance of inside pressure over outside pressure of the diaphragm device the annular seals ID and H are not stretched nor strained in tension and the forces acting o'n the sealed connection are forces of compression so that very little, if any, distortion or disruption of the seals occurs, with the result that the amount of restitution, and therefore hysteresis, is greatly reduced and the possibility of leaks is substantially eliminated, the solder acting as a seal between the diaphragms 6 and 'i and the supporting shell 3.

There is thus provided a novel and improved method of making an expansible diaphragm device having the diaphragms thereof so arranged that there is no tendency of disruption of the seal between said diaphragms and the supporting shell to which they are Secured. The annular sealing connection between the supporting shell and the diaphragms is also Situated and joined thereto so that movements of the diaphragms due to changes of preponderating internal pressure within the diaphragm device does not stretch the scaling material of the connection. The diaphragm flange portion extends inwardly of the bounding shell at an angle' defining with said shell an obtuse angle at the preponderating pressure side, and the diaphragm fiange portion is soldered to the shell in such a way that the solder is not stretched or subjected to tension due to diaphragm movements occasioned by changes in such preponderating pressure.

While two forms of expansible diaphragm devices embodying the method of the invention have been illustrated and described, various changes in the sequence of steps of the method and in the form and construction of the devices, which will now appear to those skilled in the art, may be made without departing from the scope of the invention. Reference is, therefore, to be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. The method of making expansible diaphragm devices, which method comprises forming a pair of corrugated disc-shaped fiexible diaphragms so as to provide peripheral flanges thereon projecting at an acute angle out of the planes' thereof. providing a cylindrical supporting shell for said diaphragms, positioning said diaphragms in said shell at opposite ends thereof with their flanges projecting toward each other and abutting against the inner surface of said shell, and joining said fianges to the inner surface of said shell to provide a sealed air tight connection therebetween, thereby forming an air-tight closed chamber between the two diaphragms.

2. The method of making expansible diaphragm devices, which method comprises forming a pair of corrugated disc-shaped flexible dia- The diaphragms 6 and 'I- phragms so as to provide peripheral flanges,

thereon projecting at an acute angle out of the planes thereof, providing a cylindrical supporting shell for said diaphragms, positioning said diaphragms in said shell at opposite ends thereof with their flanges projecting toward each other, spinning the ends of said shell over the flanges of the diaphragms in abutting relation thereto.

a and joining the spun-over ends of said shell with the flang'es of the diaphragms to form a sealed air tight connection therebetween, thereby forming an air-tight closed chamber between the two diaphragms.

3. The method of making expansible diaphragm devices, which method comprises forming a pair of corrugated disc-shaped flexible diaphragms so as to provide' peripheral fianges thereon projecting at an acute angle out of the planes thereof, providing a cylindrical supporting shell for said diaphragms and of substantially' the same inside diameter as the diameterof said,

diaphragms, positioning said diaphragms in said shell at opposite ends thereof and a suflicient distance inwardly of said ends to provide end portions on said shell for spinning over the vide a fiange, inserting one of said diaphragms from the other end of said shell, positioning said diaphragm in'said shell against the spun `end so that the `flange of said diaphragm abuts the fiange of the spun end of the shell, joining said fianges together to provide a sealed air tight coni nection therebetween, inserting the other diaphragm into the shell with the fiange facing the shell to close the open en'd of said shell. spin- .ning said open end of the shell inwardly to form a fiange providing an abutment for the fiange of the second diaphragm, and joining said last two fianges to provide a sealed air tight connection therebetween. i i

5. The method of making expansible diaphragm devices, which method comprises forming a. pair of circular flexible diaphragms so as' to provide peripheral flanges thereon proecting I out of the planes thereof, providing a cylindrical supporting shell for said diaphragms, positioning said diaphragms in said-shell at opposte ends thereof with their flanges projecting toward each other and against the inner surface or said shell. and joining said fianges to the inner surface oi said shell to provide a sealed air tight connection therebetween.

6. The method of making expansible diaphragm devices, which method comprises forming a pair of circular flexible diaphragms so as to provide peripheral fianges thereon projecting out of the planes thereof, providing a cylindrical supporting shell for said diaphragms, positioning said .diaphragms in said shell at opposite ends thereof with their flanges projecting toward each other, spinning the ends of said shell over the flanges of the 'diaphragms in abutting relation thereto, and joining the spun-over ends of said shell with the flanges of the diaphragms to form a sealed air tight connection therebetween.

'7. The method of making expansible diaphragm devices, which method comprses forming a pair of circular flexible diaphragms so as to provide peripheral fianges thereon, providing a cylindrical supporting shell for said diaph'ragms and of substantially the same inside diameter as the diameter of said diaphragms, positioning said diaphragms in said shell at opposite ends thereof and a suficient distance inwardly of said ends to provide end portions on said shell for spinning over the fianges of the diaphragms, spinning said ends over said flanges, and joining said spun-over ends with said flanges to form a sealed air tight connection therebetween.

8. The method of making expansible diaphragm devices, which method comprises forming a pair of corrugated disc-shaped fiexible diaphragms so as to provide peripheral fianges thereon projecting at an acute angle out of the planes thereof, providing a cylindrical supporting shell for said diaphragms, spinning one end of said shell inwardly to provide a fiange projecting inwardly at an acute angle, inserting one of said diaphragms from the other end of said shell, positioning said diaphragm. in said shell against the spun end so that the fiange of said diaphragm abuts the fiange of the spun end of the shell, joining said flanges together to provide a sealed air tight connection therebetween. inserting the other diaphragm into the shell with the fiange facing the shell to close the open end of said shell, spinning said open end of the shell inwardly to form a second fiange projecting inwardly at an acute angle and providing an abutment for the fiange of the second diaphragm,

' and joining said last two flanges to provide a v the two diaphragms. v

WLADIJMIR A. REICHEL. 

